Device for extracting blanks from a stack

ABSTRACT

A device for extracting blanks, which are to be formed into envelopes, one at a time from a stack of blanks comprises a first lever device with a suction nozzle which engages the bottommost blank by suction and bends one edge of the blank downwardly. A second lever device operates a plunger to insert the plunger between the bent down edge of the bottommost blank and blanks thereabove, and a third lever device which operates a device to lift the blanks above the bottommost blank off the bottommost blank so that the latter can be extracted by means of a rotating roller. All three lever devices have respective cam follower rollers which engage in a single elliptical cam track groove in one face of a disc cam which is rotatable about an axis, the groove being eccentric to the axis.

United States Paten Pahlitzsch [4 1 Aug. 8, 1972 [S4] DEVICE FOREXTRACTING BLANKS FROM A STACK [72] Inventor:

I 67, Berlin, Germany [22] Filed: July 9, 1970 [21] Appl. No.: 53,555

[30] Foreign Application Priority Data July 17, 1969 Germany ..P 19 37080.0

52 U.S. c1..... ..271/29 51 in. C1 ..B65h 3/10, B65h 3/50 [58] Field 61Search ..271/29, 32, 23

[56] References Cited UNITED STATES PATENTS 3,380,353 4/1968Mitterrnayer ..-..271/29 x 3,008,706 11/1961 Heigl et al ..271/29 x3,567,559 3/1971 Dullinger ..271/29 x 2,954,225 9/1960 Novick ..271/29 xBruno Pahlitmch, Gneisemaustrasse I Primary Examiner-Joseph WegbreitAssistant Examiner-Bruce H. Stoner, Jr.

Attorney-Karl E. Ross ABSTRACT A device for extracting blanks, which areto be formed into envelopes, one at a time from a stack of blankscomprises a first lever device with a suction nozzle which engages thebottommost blank by suction and bends one edge of the blank downwardly.A second lever device operates a plunger to insert the plunger betweenthe bent down edge of the bottommost blank and blanks thereabove, and athird lever device which operates a device to lift the blanks above thebottommost blank off the bottommost blank so that the latter can beextracted by means of a rotating roller. All three lever devices haverespective cam follower rollers which engage in a single elliptical camtrack groove in one face of a disc cam which is rotatable about an axis,the groove being eccentric to the axis.

8 Clains, 4 Drawing Figures PATENTEDAUB M 7 3,682,471 SHEET 3 BF 4mvenior:

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PATENTEDAUG 8 i972 3,682,471

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DEVICE FOR EXTRACTING BLANKS FROM A STACK FIELD OF THE INVENTION Thepresent invention relates to a device for extracting the bottommost oneof a stack of blanks of sheet material such for example as blanks forenvelopes, bags or the like.

BACKGROUND OF THE INVENTION In the automatic production of envelopes,one known method commences with pre-cut envelope blanks which arestacked one above the other and placed thus in the machine formanufacturing the envelopes. In so doing, the individual blanks aresuccessively drawn from the bottom of the stack and supplied to aconveyor path upon which all the operations required to convert theblank into a finished envelope or bag, are carried out. In the knownsystem, in order to withdraw the bottommost blank of the stack, threesuccessively operating lever devices are used, one of which carries asuction device, the other a plunger and the third two stack lifters withair-blast nozzles. In withdrawing the blank, firstly the front edge isgripped by the suction device and bent downwards. Into the space thusopened between the bottommost blank and the stack, a plunger is insertedwhich keeps the front edge of the stack in position. Then, into saidsame space, the stack lifters, which are equipped with airblast nozzles,are introduced. By means of the air-blast the bottommost blank isseparated, with the assistance of the lifting of the stack, so that thisblank can be withdrawn freely. In this known embodiment, the timesequence and time of operation of the individual lever devices, arecontrolled by three cams. The use of three separate such cams for thethree lever devices makes for substantial constructional outlay; also,the provision of these cams necessitates a larger installation space.Finally, a further drawback of this arrangement resides in the fact thatthe cams, which must be precisely adjusted in relation to one another,tend over long periods of operation to become slightly out of phase withone another so that the time relationship between the operations of theindividual lever devices is changed, leading thus inevitably to faultyoperation.

OBJECT OF THE INVENTION The object of the present invention is to avoidthese drawbacks and create a device which is distinguished by minimalconstructional and installational outlay, and in which alteration in themutual positions of the lever devices, is excluded.

SUMMARY OF THE INVENTION According to the invention there is provided adevice for extracting the bottommost one of a stack of blanks of sheetmaterial, comprising a lever device adapted to bend down a front end ofthe bottommost blank and including a suction nozzle, a lever deviceconnected to a plunger adapted to be inserted between the bent down edgeof the bottom blank and the stack, and an additional lever devicecarrying stack lifter means with at least one air-blast nozzle, acommon, closed path cam system being provided to control all the leverdevices in respect of operating sequence and time of operation.

Preferably the closed path of the cam system consists of anelliptically-shaped cam track groove disposed in a rotating disceccentrically vis-a-vis the disc center, which cam track is disposedsymmetrically vis-a-vis a plane perpendicular to the disc and passingthrough the center of rotation, follower rollers located at free ends ofthe lever devices being guided in said cam track groove at distancesfrom one another.

Preferably, follower rollers of the lever devices carrying the stacklifters with the air-blast nozzles, and carrying the plunger, arelocated diametrically opposite one another in the cam track and thethird follower roller is located between them, proximal to the followerroller associated with the stack lifters.

The above-mentioned disc containing the cam track is advantageouslyarranged in a closed housing, and free ends of levers carrying thefollower rollers are carried in bearings arranged in the housing. Also atoothed sector may be attached to a free end of each lever carrying afollower roller, each sector being in engagement with a gear, the gearsrespectively controlling the movements of suction nozzle, plunger andstack lifters.

Finally, the plunger is preferably arranged for longitudinaldisplacement in a mounting secured to the housing, and is formed at itsend as a rack which engages with a gear; the gear associated with therack and that associated with a cam-operated lever each carry a radialarm, the two arms being attached to one another by a link.

DESCRIPTION OF THE DRAWING The accompanying drawing illustrates anexample of a device in accordance with the invention. In the drawing:

FIG. 1 schematically illustrates an assembly drawing; FIG. 2 is anillustration in accordance with FIG. 1 in which only the liftermechanism for the front edge of the bottom blank in the stack, has beenshown;

FIG. 3 is an illustration in accordance with FIG. 1 in which only thelever device operating the plunger, has been illusrtated; and

FIG. 4 is an illustration in accordance with FIG. 1 in which only thelever device operating the stack lifters, has been shown.

SPECIFIC DESCRIPTION FIG. 1 illustrates a stack 1 consisting of stackedblanks of sheet material. Beneath the stack an extraction roller 2 isarranged. Also arranged near the stack is a closed housing 3 in which adisc cam 4 rotates, the cam containing a cam-track groove 5 in whichthere are engaged three levers, namely, a lever 8 for a device forbending down the bottommost blank, a lever 17 for a plunger 31 and alever 31 for a stack lifter. All the bearings for the cam 4 and threelever devices are arranged on the housing 3. For purposes of clarity ofillustration, FIGS. 2 to 4 each illustrate one of the three leverdevices.

As FIG. 2 shows, the lever 8 is guided by means of a follower roller 9in the cam track 5. The lever 8 is rotatable upon a shaft 10 and hasattached to it a toothed sector 7 which meshes with a gear 12 carried ona spindle 13. The gear 12 carries an arm 14 which, at its other end,carries a suction head 15 with the suction nozzle 16; when the disc cam4 is rotated in the clockwise direction, said lever 8 is pivoted upwardsabout the shaft 10, the sector 11 moving towards the left. Consequently,the gear 12 is rotated counterclockwise and in so doing pivots the arm14, with the suction head 15, downwards so that the front edge of theblank located buttommost in the stack 1, is bent downwards.

Then, as FIG. 3 shows, the plunger 31 enters the space between the stackand the edge of the bottom blank. To this end, the lever 17 is guided bymeans of a follower roller 18 in the cam track 5. The lever 17 isarranged upon a shaft 19 and is connected to a toothed sector 20 whichmeshes with a gear 21 mounted on a spindle 22 and carrying an arm 23,the latter being linked by a link 24 to an arm 25 which is rotatablymounted on a shaft 26 and secured to a gear 27 meshing with a toothedrack 30 of. a plunger rod 28. The plunger rod 28 is mounted in alongitudinally displaceable manner in a guide 29. At its front end itcarries the plunger 31. When the externally located crest of the trackreaches the follower roller 18 during the course of the clockwiserotation of the cam disc 4, the lever 17 is pivoted downwards and thenupwards, the toothed sector connected to it rotates towards the rightand then the left about the spindle 19, the gear 21 is rotatedcounterclockwise and then clockwise around the spindle 22, and the arm23, the link 24 and the arm are moved towards the left and then theright so that the gear 27 engaging with the rack 30 of the plunger rod28 displaces said rod 28 in the guide 29 towards the right and then theleft with the consequence that the plunger 31 penetrates into the spacebetween the stack and the bottommost blank.

With further rotation of the disc cam 4 in the clockwise direction, thelever mechanism of the stack lifter (FIG. 4) comes into operation. Tothis end, a lever 32 engages the cam track 5 by means of a followerroller 33, lever 32 being pivotable about a spindle 34 and carrying atoothed sector 35 engaging with a gear 36, the latter in turn meshingwith a gear 37. The gear 37 carries an arm 38 at whose end, lifters 39are located, the latter being provided at their top surfaces withair-blast nozzles 40. When the plunger 31 has penetrated into the spacebetween stack and bottommost blank, in the manner shown in FIG. 3, withfurther rotation of the disc cam 4, the lever 32 is pivoted upwards andthen downwards so that the toothed sector 35 attached to it movestowards the left and then the right and the gear 36 is rotated clockwiseand. then counterclockwise. The gear 37 is rotated counterclockwise andthen clockwise by the gear 36 so that the arm 38 secured to said gear 37and carrying the lifters 39, enters the space opened up by the plunger31, the air-blast nozzles 40 located on the topside of the lifter 39lifting the stack away from the bottom blank so that the latter can bewithdrawn freely by the extraction roller 2 and conveyed to a conveyor.

The drive to the disc cam 4 is effected through a gear 6 driven by themachine.

By the provision in accordance with the invention, of a single cam disccontaining a cam track (groove), which disc is arranged in a closedhousing also containing the three lever devices, a compact, closedconstruction is obtained. Because all three lever devices are guided inone and the same cam track and are mounted in a fixed housing, mutualalteration of the settings of the three lever arrangements is out of thequestion so that they are always operated in the same timedrelationship. The closed design of the housing prevents any ingress ofdust and impurities so that the device in accordance with the inventionoperates completely reliably. Indeed, the cam can be arranged to operatein an oil bath. By the design of the cam track as a groove, the heavyduty tension and compression springs required in association withconventional cams in order to maintain the levers in continuousengagement with the cam tracks, are obviated. Furthermore, the device inaccordance with the invention ensures quieter and more rapid running.

I Claim:

1. Apparatus for supporting a stack of blanks of sheet material one ontop of another and for separating a bottommost blank in the stack fromother blanks in the stack, comprising:

means for supporting the stack of blanks one on top of another;

a first lever device including a suction nozzle and operable to engagethe nozzle with the bottommost blank in the stack and bend down one edgeof said bottommost blank;

a second lever device operatively connected to a plunger and operable toinsert the plunger between the bent down edge of said bottommost blankand blanks above the bottommost blank;

a third lever device operatively connected to a device for liftingblanks which are above the bottommost blank in the stack;

a rotatable single track cam device;

first, second and third cam-follower means engageable with the singletrack of said cam device and operatively connected to said first, secondand third lever devices respectively;

and drive means adapted to rotate said cam device in a direction so asto produce sequential operation of said first lever device, said secondlever device and said third lever device.

2. Apparatus for supporting a stack of blanks of sheet material one ontop of another and for separatinga bottommost blank in the stack fromother blanks in the stack, comprising:

means for supporting the stack of blanks one on top of another;

a first lever device including a suction nonle and operable to engagethe nozzle with the bottommost blank in the stack and bend down one edgeof said bottommost blank;

a second lever device operatively connected to a plunger and operable toinsert the plunger between the bent down edge of said bottommost blankand blanks above the bottommost blank;

a third lever device operatively connected to a device for liftingblanks which are above the bottommost blank in the stack;

a rotatable cam device;

first, second and third cam-follower means engageable with said camdevice and operatively connected to said first, second and third leverdevices respectively;

and drive means adapted to rotate said cam device in a direction so asto produce sequential operation of said first lever device, said secondlever device and said third lever device, said rotatable cam devicecomprising a disc which is rotatable about an axis and is formed with anelliptical groove in one face of the disc, said groove being eccentricto said axis and said first, second and third cam follower means allengaging in said groove.

3. Apparatus as defined in claim 2 wherein said second and third camfollower means are arranged substantially diametrically opposite eachother relative to said axis.

4. Apparatus for supporting a stack of blanks of sheet material one onetop of another and for separating a bottommost blank in the stack fromother blanks in the stack, comprising:

means for supporting the stack of blanks one on top of another;

a first lever device including a suction nozzle and operable to engagethe nozzle with the bottommost blank in the stack and bend down one edgeof said bottommost blank;

a second lever device operatively connected to a plunger and operable toinsert the plunger between the bent down edge of said bottommost blankand blanks above the bottommost blank;

-a third lever device operatively connected to a device for liftingblanks which are above the bottommost blank in the stack;

a rotatable cam device;

first, second and third cam-follower means engageable with said camdevice and operatively connected to said first, second and third leverdevices respectively;

drive means adapted to rotate said cam device in a direction so as toproduce sequential operation of said first lever device, said secondlever device and said third lever device; and

a closed housing and bearing means within said housing carrying saidfirst, second and third lever devices and cam follower means within saidhousing.

5. Apparatus for supporting a stack of blanks of sheet material one ontop of another and for separating a bottommost blank in the stack fromother blanks in the stack, comprising:

means for supporting the stack of blanks one on top of another;

a first lever device including a suction 'noule and operable to engagethe nozzle with the bottommost blank in the stack and bend down one edgeof said bottommost blank;

a second lever device operatively connected to a plunger and operable toinsert the plunger between the bent down edge of said bottommost blankand blanks above the bottommost blank;

a third lever device operatively connected to a device for liftingblanks which are above the bottommost blank in the stack;

a rotatable cam device;

first, second and third cam-follower means engageatommost blank in thestack from other blanks in the stack, comprising:

means for supporting the stack of blanks one on top of another;

a first lever device including a suction nozzle and operable to engagethe nozzle with the bottommost blank in the stack and bend down one edgeof said bottommost blank;

a second lever device operatively connected to a plunger and operable toinsert the plunger between the bent down edge of said bottommost blankand blanks above the bottommost blank;

21 third lever device operatively connected to a device for liftingblanks which are above the bottommost blank in the stack;

a rotatable cam device;

first, second and third cam-follower means engageable with said camdevice and operatively connected to said first, second and third leverdevices respectively;

drive means adapted to rotate said cam device in a direction so as toproduce sequential operation of said first lever device, said secondlever device and said third lever device;

guide means guiding said plunger for longitudinal displacement of saidplunger;

a toothed rack member connected to said plunger, and a first gear inmesh with said toothed rack member, said second lever device comprisinga first lever connected to said first gear;

a link member pivotally connected to said first lever;

a second lever pivotally connected to said link member;

a second gear connected to said second lever;

a toothed sector in mesh with said second gear; and

a third lever connected to said second gear, said second cam followermeans being connected to said third lever.

7. Apparatus as defined in claim 2 and comprising means for extractingthe bottommost blank from the stack.

8. Apparatus as defined in claim 7 wherein said means to extract thebottommost blank from the stack comprises: a rotatable roller which isengageable with the bottommost blank; and drive means to rotate theroller.

1. Apparatus for supporting a stack of blanks of sheet material one ontop of another and for separating a bottommost blank in the stack fromother blanks in the stack, comprising: means for supporting the stack ofblanks one on top of another; a first lever device including a suctionnozzle and operable to engage the nozzle with the bottommost blank inthe staCk and bend down one edge of said bottommost blank; a secondlever device operatively connected to a plunger and operable to insertthe plunger between the bent down edge of said bottommost blank andblanks above the bottommost blank; a third lever device operativelyconnected to a device for lifting blanks which are above the bottommostblank in the stack; a rotatable single track cam device; first, secondand third cam-follower means engageable with the single track of saidcam device and operatively connected to said first, second and thirdlever devices respectively; and drive means adapted to rotate said camdevice in a direction so as to produce sequential operation of saidfirst lever device, said second lever device and said third leverdevice.
 2. Apparatus for supporting a stack of blanks of sheet materialone on top of another and for separating a bottommost blank in the stackfrom other blanks in the stack, comprising: means for supporting thestack of blanks one on top of another; a first lever device including asuction nozzle and operable to engage the nozzle with the bottommostblank in the stack and bend down one edge of said bottommost blank; asecond lever device operatively connected to a plunger and operable toinsert the plunger between the bent down edge of said bottommost blankand blanks above the bottommost blank; a third lever device operativelyconnected to a device for lifting blanks which are above the bottommostblank in the stack; a rotatable cam device; first, second and thirdcam-follower means engageable with said cam device and operativelyconnected to said first, second and third lever devices respectively;and drive means adapted to rotate said cam device in a direction so asto produce sequential operation of said first lever device, said secondlever device and said third lever device, said rotatable cam devicecomprising a disc which is rotatable about an axis and is formed with anelliptical groove in one face of the disc, said groove being eccentricto said axis and said first, second and third cam follower means allengaging in said groove.
 3. Apparatus as defined in claim 2 wherein saidsecond and third cam follower means are arranged substantiallydiametrically opposite each other relative to said axis.
 4. Apparatusfor supporting a stack of blanks of sheet material one one top ofanother and for separating a bottommost blank in the stack from otherblanks in the stack, comprising: means for supporting the stack ofblanks one on top of another; a first lever device including a suctionnozzle and operable to engage the nozzle with the bottommost blank inthe stack and bend down one edge of said bottommost blank; a secondlever device operatively connected to a plunger and operable to insertthe plunger between the bent down edge of said bottommost blank andblanks above the bottommost blank; a third lever device operativelyconnected to a device for lifting blanks which are above the bottommostblank in the stack; a rotatable cam device; first, second and thirdcam-follower means engageable with said cam device and operativelyconnected to said first, second and third lever devices respectively;drive means adapted to rotate said cam device in a direction so as toproduce sequential operation of said first lever device, said secondlever device and said third lever device; and a closed housing andbearing means within said housing carrying said first, second and thirdlever devices and cam follower means within said housing.
 5. Apparatusfor supporting a stack of blanks of sheet material one on top of anotherand for separating a bottommost blank in the stack from other blanks inthe stack, comprising: means for supporting the stack of blanks one ontop of another; a first lever device including a suction nozzle andoperable to engage the nozzle with the bottommost blank in the stack andbend down one edge of saId bottommost blank; a second lever deviceoperatively connected to a plunger and operable to insert the plungerbetween the bent down edge of said bottommost blank and blanks above thebottommost blank; a third lever device operatively connected to a devicefor lifting blanks which are above the bottommost blank in the stack; arotatable cam device; first, second and third cam-follower meansengageable with said cam device and operatively connected to said first,second and third lever devices respectively; and drive means adapted torotate said cam device in a direction so as to produce sequentialoperation of said first lever device, said second lever device and saidthird lever device, at least one of said lever devices comprising alever pivotally mounted on a pivot and connected firstly to a rollerforming the respective cam follower means and secondly to a toothedsector which is in engagement with a gear.
 6. Apparatus for supporting astack of blanks of sheet material one on top of another and forseparating a bottommost blank in the stack from other blanks in thestack, comprising: means for supporting the stack of blanks one on topof another; a first lever device including a suction nozzle and operableto engage the nozzle with the bottommost blank in the stack and benddown one edge of said bottommost blank; a second lever deviceoperatively connected to a plunger and operable to insert the plungerbetween the bent down edge of said bottommost blank and blanks above thebottommost blank; a third lever device operatively connected to a devicefor lifting blanks which are above the bottommost blank in the stack; arotatable cam device; first, second and third cam-follower meansengageable with said cam device and operatively connected to said first,second and third lever devices respectively; drive means adapted torotate said cam device in a direction so as to produce sequentialoperation of said first lever device, said second lever device and saidthird lever device; guide means guiding said plunger for longitudinaldisplacement of said plunger; a toothed rack member connected to saidplunger, and a first gear in mesh with said toothed rack member, saidsecond lever device comprising a first lever connected to said firstgear; a link member pivotally connected to said first lever; a secondlever pivotally connected to said link member; a second gear connectedto said second lever; a toothed sector in mesh with said second gear;and a third lever connected to said second gear, said second camfollower means being connected to said third lever.
 7. Apparatus asdefined in claim 2 and comprising means for extracting the bottommostblank from the stack.
 8. Apparatus as defined in claim 7 wherein saidmeans to extract the bottommost blank from the stack comprises: arotatable roller which is engageable with the bottommost blank; anddrive means to rotate the roller.